After an oil well has been in operation for some time, its productivity often diminishes to the point at which the operation of the wells is either marginal or entirely unfeasible from a commercial viewpoint. It is frequently the case, however, that substantial qualities of crude oil remain in the ground in the regions of these unproductive wells but cannot be liberated by conventional techniques.
It is believed that there are a number of causes for the decreased productivity of such wells. A principal cause is the build up of deposits that tend to close perforations in the well casing, thereby preventing the oil from flowing freely to the pump. The composition of these deposits varies from one geographical region to another, and the deposits may be characterized in the art as either "wax" or "chalk".
Another reason for decreased productivity is a decrease in the fluid pressure that causes crude oil to flow, constantly refilling the area in which the pump is located. This pressure is largely attributable to the presence of natural gas within the oil. Often, a major portion of the natural gas present in the vicinity of a well escapes when the well is first opened. It is believed that additional gas remains in the well, perhaps entrained within the oil, and continues to contribute to the fluid pressure. Eventually, as more and more oil is liberated, a larger proportion of the gas escapes or is removed and the pressure diminishes.
An objective of the present invention is to provide an effective and expeditious technique for removing deposits that clog the perforations of oil well casings. A further objective is to provide a technique for stimulating wells to increase the pressure and improve the flow of crude oil into the casings.